docs: def is_valid(self):
          '''
          For this form to be considered valid, there must be not only no errors, but also no messages on
          the request that need to be shown.
          '''
  
          valid = super(RegistrationContactForm,self).is_valid()
          msgs = messages.get_messages(self._request)
  
          # We only want validation messages to show up once, so pop messages that have already show up
          # before checking to see if any messages remain to be shown.
          prior_messages = self._session.pop('prior_messages',[])
          remaining_messages = []
  
          for m in msgs:
              m_dict = {'message': m.message, 'level': m.level, 'extra_tags': m.extra_tags}
              if m_dict not in prior_messages:
                  remaining_messages.append(m_dict)
  
          if remaining_messages:
              self._session['prior_messages'] = remaining_messages
              self._request.session.modified = True
              return False
          return valid